Grinding-mill.



J. N. BOSCH, Jn.

Patented Feb. 14, 1911.

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TIE. J.

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J. N. BOSCH, JR. GRINDING MILL.

APPLICATION FILED 001'. 27, 1908.

984,505. Patented Feb. 14, 1911.

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J. N. BOSCH, JR-

GRINDING MILL. APPLIUATIOF FILED 001. 27, 1908.

Patented Feb. 14, 1911.

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J. N. BOSCH, J3. GRINDING MILL.

APPLICATION PILED OUT. 27, 190B.

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Wit ease:

J. N. BOSCH, JR.

GRINDING MILL. 1

APPLICATION FILED OUT. 87, 1908.

Patented Feb.14,1911.

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APPLIOATIOH FILED OUT. 27, 1908.

Ptented Feb. 14, 1911.

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GBINDIN G MILL. APPLICATION FILED OUT. 27, 1909.

Patented Feb. 14, 1911.

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JOHN N.

BOSCH, JR., OF CEMENTON, PENNSYLVANIA.

GRINDING-MILL.

Specification of Letters Patent.

Application filed October 27, 1908.

Patented Feb. 14, 1911. Serial No. 459,789.

To all whom it may concern:

Be it known that I, Join: N. Boson, Jr., a citizen of the United States,residing at Cementon, in the county of Lehigh, State of Pennsylvania,have invented certain new and useful Improvements in Grinding-Mills; andI do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same.

The present invention relates, generally, to improvements in grindingmills, and it has for its primary object the provision of a mill of thetype specified which includes novel grinding apparatus, a novel arrangement of the component parts of such apparatus with respect to eachother, a novel mechanism for driving the movable member of the grindingapparatus, and novel mechanism for feeding the material to be treated tosaid apparatus.

To this end, the invention resides in the provision of a grindingapparatus whose upper or movable member is secured to the shaft of asteam turbine.

The invention resides more especially .in the particular devicesemployed for feeding the material to be treated to the grindingmechanism and to the particular construction of the latter which is ofthe ball type and includes two separate series of rollers which operatein different horizontal planes, the material being fed initially to thelower series of rollers for treatment thereby, after which it isdelivered to the upper series of rollers, subjected to the crushingaction of the same, and finally removed in a finely divided state fromthe mill.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which corresponding parts or tea-- tures, asthe case may be, are designated by the same reference charactersthroughout the several views.

Of the said drawings, Figure 1 is a front elevationo't' the completeinvention. llig. is a vertical section therethrough. Fig. 3 is a planview of the governor with the casing thereof broken away, showing thegovernor arms in their extended position. Fig. .t is a vertical sectiontaken diametrically through Fig. 3, the governor arms being shown intheir normal or retracted position. Fig. is a horizontal section throughthe turbine. Fig. 6 is a front elevation, partly in section of theturbine, a portion of the central member of the turbine being brokenaway, to disclose the inner or rotating member. Fig. 7 is an enlargedfragmental section taken vertically through the turbine on the line T-Tof Fig. 5, shmving the single valve rod in its raised position. Fig. 8is a similar view on the line 88 of Fig. 5, illustrating the doublevalve rod in its lowered position, the plane of said section being atright angles to that of Fig. '7. Fig. 9 a plan view of the rocking leverfor operating the valve rods. Fig. 10 is a plan view, partly in sectionof the grinding mechanism. Fig. 1.1 is a horizontal section through thelower portion of said mechanism. -Fig. 12 a vertical section takenradially through the grinding mechanism, showing the feeding devicesemployed in connection therewith. Fig. 13 is a fragn'iental. verticalsection showing a modified form of grinding roller. Fig. 11 isa verticalsection taken on the line 1 1-1 1 of Fig. 10, illustrating the shutterswhich regulate the passage of dust and other impurities to the dustchamber. Fig. 15 is an enlarged detail view of a modified form ofshutter. Fig. .16 is an enlarged vertical section through Fig. 15.

Referring more particularly to the drawings, A designates, generally,the turbine, to which steam is supplied from the valve chamber l; ineonnnnnieation with the main supply pipe (not shown) C the governorconnected with the shaft of the turbine; and D the devices for feedingthe grain or other material to the grinding mechanism, which latter isgenerally designated by the reference character I).

The turbine A consists of three nested concentric cylindrical shells 1,2 and 3, and upper and lower heads l; and 5, respectively, whoseprojecting peripheral edges are conncctcd together by bolts (3. Theouter and central shells i1. and 2 are stationary, and the former isprovided at one side with an inlet opening 7 formed therethrough midwaybe tween its top and bottom edges, in which opening is fitted one end ofan outlet pipe 8, whose other end is titted in an opening 9 formed inthe lower head 10 of the cylindrical valve chamber B, the vertical wall11 of which is connected by a brace 12 with the turbine head t abovementioned.

The outer shell 1 has both its inner and its outer faces plane andunbroken except by the above mentioned inlet opening 7 and by 'inafter.

a pair of outlet or exhaust openings 1?) and 14 arranged one above theother and formed in the diametrically opposite side of the shell fromthe opening 7, said exhaust openings being referred to more specificallhere- The central shell 2 has formed upon its outer face a series ofcircumscribing horizontal ribs 15 arranged parallel with and in spacedrelation to each other, each rib being provided in turn with a circumscribing groove in which a packing ring 16 is disposed, the outerfaces of the rings contacting with the inner face of the shell 1. Thespaces between adjacent ribs thus form annular steam chambers 17, theopening 7 comnninicating directly with the cen tral chamber, as shown inFigs. (3 and 7. Directly opposite said inlet opening there is located anendwise movable vertical valve rod 18 slidable through alining openingsformed in the ribs 15, said rod having a length sufficient to extendsome distance above the upper head at of the turbine, its upper endbeing pivotally connected to the adjacent end of a horizontal rockinglever 19, which, intermediate its ends. is enlarged to form a collar 20through which the turbine shaft 21 passes, said shaft, collar andshoulder being provided with registering perforations for the receptionof a horizontal pivot bolt 22. The other end of the lever is providedwith a cross pin 23 to whose ends are pivotally connected the upper endsof a pair of parallel valve rods 2% and 25, which pass through aliningopenings formed through the ribs 26 located upon the inner face of theshell 2 and lying in the same horizontal planes with the correspondingribs 15, which latter terminate flush with the adjacent longitudinaledges of the vertical shoulder 27 which extends from top to bottom ofsaid shell and is formed by thickening the shell at such point. Thespaces between adjacent ribs 27 form steam chambers 28.

The rod 18 has a longitudinal series of seats 29 formed in one sidethereof, as shown in Fig. 7, the ribs 30 between adjacent seats beingprovided with packing rings 31. The rods 2% and are in like mannerprovided with series of seats 82 and 33, which seats and the ribs 3% and3.3 therebetween are disposed out of alinement with each other, as shownin Fig. 8, the ribs of both series carrying packing rings 36. The seatsin the rod 18 have a length exactly equal to the height of thecorresponding chambers 29 and the ribs therefore have a length equal tothat of the ribs 15. In like manner, the height of the ribs 34: and 35is equal to that of the ribs 26.

The vertical wall of each steam chamber 17 has formed therein acireumscribing series of ports 37 each of which extends inwardly throughthe shell 2 at an angle of about 30 and opens through the vertical faceof a bucket 38, said buckets being formed in the inner face of saidshell, and being similar in shape to the series of buckets 39 which areformed in the outer face of the shell 3 which rigidly connected in anypreferred manner with the turbine shaft 21, the arrangement of thebuckets of the shell 2 with respect to those of the shell 3 being suchthat the steam which enters the annular chambers 17 will pass throughthe ports 37 and buckets 38 and will impinge directly against thevertical faces of the buckets 39, forcing the shell 3, in which saidbuckets are formed, and with it the turbine shaft to rotate, as will beunderstood.

The speed at which the turbine is driven is controlled both by thegovernor C and by the rocking lever 19, the governor serving toautomatically control the flow of steam to the turbine, while themanually-operated lever governs to a large extent the course of thesteam upon entering the turbine. The first-mentioned apparatus as shownin Figs. 2, 3 and 4, comprises a pair of oppositelydisposedsemi-circular hoops 41 whose mutually-adjacent ends are connectedtogether by expansible coil-springs 42. Intermediate its ends each hoopis fastened to the forward end of a wedge-shaped block 43 whose obliqueupper face is in contact with the adjacent similarly-inclined arm 4st ofthe stem 1-5 of a cut-off valve, whose head 16 is movable into and outof a seat 4:7 formed in the horizontal partition plate 18 disposedwithin the interior of the valve chamber B. The base of each block restsupon a horizontal arm. 49 secured at its inner end to the turbine shaftadjacent the upper end thereof, the extreme upper portion of the saidshaft being slotted longitudinally at opposite sides to permit thepassage of the arms 14 therethrough. The arms 44 and 19 each consist ofa pair of rails connected by antifriction rollers 50, the distancebetween the rails of each arm being slightly greater than the width ofthe blocks, whose upper and lower faces are therefore in contact withsaid roll ers. By reason of this construction, it will be apparent thatwhen the speed of the turbine becomes excessive, the hoops 41 will movein opposite directions away from each other, thus imparting a similarmovement to the blocks 43, the movement of said blocks raising the arms4st, and with them the cutoff valve, to whose stem said arms are rigidlyconnected. The upward movement of the cut-off valve brings its head intothe seat 47 and thus shuts off the supply of steam from the main supplypipe (not shown) to the inlet pipe 8. hen the speed of the turbine hasdecreased sufliciently to permit the hoops and blocks to move inwardlyunder the tension of the springs 4-2, the cut-off valve will be free tomove downwardly to its normal position, whereupon the steam is free toHow through the seat or opening 47 into the valve chamber B and thenceto the inlet pipe. The action of the governor is thus automatic, as willbe understood. In like manner, the speed of the turbine may be controlled to a certain extent by means of the lever 19. In the normalposition of said lever, its left hand end is elevated and its right handend depressed, the valve rod 18 being in consequence, lowered and therods 24 and 25 raised, as shown in Fig. (3. \Vhen the first mentionedrod is in such position, its ribs 30 are disposed exactly within theopenings in the ribs 1:"), the seats 29 in said rod registering with theannular chambers 17 between said ribs 1:"). The incoming steam thus freeto pass into the central chamber 17 only, passing through the ports 37and buckets 38 which communicate with said chamber and filling thebuckets 39, against whose vertical faces the steam strikes, thusrotating the inner shell 2 in which the last mentioned buckets areformed at a moderately low rate of speed. Vhcn the buckets 39 reach thecentral chamber 28, the steam will pass into the latter from saidbuckets, as will be apparent. As previously stated, the ribs 26 betweenadjacent chambers are likewise provided with two series of aliningopenings through which the rods 24. and 25 have an endwise movement,said rods being raised when the rod 18 is lowered. Each of the severalchan'ibers Q8 communicates with the corresponding chamber 17 through anoblique port 50, and in addition to this, the uppermost and lowermost ofsaid chambers are provided with exhaust openings 51 and which registerwith the openings 13 and 14 in the outer shell 1, the pairs of openingsreceiving the upper and lower branches and 54. ot the outlet or exhaustpipe hen the rods 24 and 25 are in their normal or lowered position, theribs ot the rod 25 will be disposed in the series 0t openings in theribs 26 with which the oblique ports 50 communicate, closing saidoblique ports, as will be understood. The other series of openings inwhich the rod Q-t slides will. however, register with the seats formedin said'rod. thus a tt'ording a communication between adjacent chambers.It will therefore be apparent that when the steam has exhausted ti-omthe buckets 39 into the central chamber 28, it will exhaust from thelatter in both directions through the last-mentioned series of openings,and will finally reach the uppermost and lowermost chambers 'lrom whichit exhausts through the pairs of openings 51 and 13, and 52 and 1 k, andthe branch pipes 53 and 54, to the outlet pipe however, it is desired tosuddenly im-roase the speed of the turbine, as for instance, when any ofthe ports leading to the buckcts in the central chamber 17 becomeclogged by grit or other loreign material, the lever '18) is rocked uponits pivot, so as to elevate the rod '18 and lower the rods 2-1; and '25,as shown in Figs. 7 and \Vhen the first mentioned rod is in suchposition, its ribs 30 are disposed directly opposite the chambers 17 andthe in-coming steam is free to tlow into all of said chambers, as willbe ap parent, passing through the ports 37 and buckets 38 and impingingagainst the vertical faces of the buckets 39, torcing the shell 3 torotati at a comparatively high rate oi." speed, the steam exhaustingfrom the buckets 35) into the chambers 28. Owing to the fact, however,that the rods 24- and 25 have been lowered by the movement of theoperating lever, the ribs 3-} formed upon the rod 2-1: will tit exactlyin one series of openings in the ribs 26, while the oblique ports 50which communicate with the other series of openings in said ribs willalso communicate with the seats 33 formed in the rod 25, said seatsintersecting said openings as shown in Fig. 8.

The steam which exhausts from the buckets 3!) into the chamber 28 willthus flow through the oblique ports 50 into the rear halves of thechambers 17, said ports extending through the shoulder 27. The steamthen passes through the ports and buckets 37 and 38 into the buckets 39as in the first instance, the speed thus attained being sufficientlyhigh to ell'ect the (.liSl0( gment of the grit or other material as willbe obvious, the actuation of the governor being likewise e'tt'ected. Itevident, therefore, that when the valve rods are in their normalposition, the governor is inoperative, since the speed at which theinner shell or piston of the turbine is rotated is too low to ettect itsactuation. XV hen however, the piston is rotating at its high speed andsuch speed becomes excessive, the governor will be operatedautomatically, thus cutting off the supply of steam to the turbine. Itwill also be apparent that the provision of the valve rods and therocking lever renders it possible to suddenly increase the speed of theturbine whenever such increase becomes necessary for any reason. Thegovernor is preferably incloscd within a dust-proof casing 56, as shownin Figs. 2 and Directly beneath the lower head 5 of the turbine, thereis secured to the turbine shalt a plate 119 provided with a pair oflaterallyprojecting ears 120 between which projects the laterally-bcutlower end ot a depending arm 121 secured to said head. These elementscooperate with each other in "Forming a gage or indicator oi therelative position oil the inner shell or piston 33 ot the turbine and Ofthe central shell 2 with respect. to each other, it being apparent thatif the turbine shaft and piston become disposed 'llO fit 984,505

from their normal position incidental to a. downward movement of theshaft from any cause, or if the outer or central shells of the turbinemove downward toward the grinding mechanism, the bent end of the arm 12will be disposed nearer to the upper car 120 than to the lower ear, thusindicating such displacement.

The grinding mechanism E, which is operated by the rotation of theturbine shaft 21 and is inclosed by a cylindrical casing 57 whichcomprises a stationary lower member or floor 58 and a rotatable uppermember consisting of inner and outer annuli 59 and 60, the former ofwhich is provided with a series of peripherally-located series ofupstanding pins (31 which are engaged between the members of a series ofpairs of spaced ears 62 radially inward from the inner periphery of theannular member (50, which latter is rigidly connected by a series ofoblique braces (33 with a cylindrical casing (3% which forms one elementof the feed mechanism 1) and has its lower end projecting through thecentral opening in the member 59, as shown in Fig. 2, there being,however, no direct connection between the casing and said member 59,which latter is forced yieldingly downward by expansible coil-springs($5 and is thus capable of a limited vertical movement with respect.- tosaid casing, said springs bearing at their upper ends against the bracesand at their lower ends against said member 59. Below the floor member58 is located a water jacket 123, as shown in Figs. 2 and 1 Between themembers and GO and the member 58, are interposed inner and outerconcentric series of balls 66 and 67 whose lower portions lit in annularraces 68 formed in the upper face of the last-mentioned member, themembers 59 and (30 having similar races ()9 and 70 formed in their underfaces, each race having a lining plate 71 of raw-hide fastened therein.The memher 60 is provided at diametrically opposite points with a pairof openings 72 in which are secured the upper ends of a pair ofoppositely-extending arcuatc scoops 78 whose widened lo wcr ends restupon the upper face of the member 58, the material ground by the seriesof balls 66 and 37 traveling up said scoops during the rotation of saidmember (30. The member 0 is further provided with a race 74 which isformed in its upper face adjacent the outer peripheral edges thereof andis disposed directly below a similar race 75 formed in the under face ofan annular member 76 disposed in spaced relation to and parallel withthe member 60, said races being each provided with a lining plate 77similar to the plates 71. Between the members 76 and (30 is interposed aseries of balls 7 8, whose upper and lower portions are received in theraces last-mentioned, said balls having a diameter approximately halfthat of the balls 66 and 67. The member 76 rests upon the balls 78 andis supported thereby.

The surfaces of the several balls 66 and 67 contact with double-endedscrapers 79 interposed therebetween, and having their upwardly-extendingstems secured to the under face of the members 59, as shown in Fig. 2,while the surfaces of the balls 78 contact in like manner, with scrapers80 carried by the member 76.

The upper end 81 of the cylindrical casing (S t above referred to isformed separate from the body portion thereof, shown in Figs. 2 and 12,and is provided with an integral laterallyextending sleeve 82 in whichis disposed a screw-conveyer 83 whose shaft 84 carries at its inner enda worm 85 which meshes with and is driven by a worm gear 86 secured tothe turbine shaft 21, the diameter of said sleeve and of said conveyergradually increasing from their outer to their inner ends.

The upper portion of the sleeve 82 is provided with a series of threeinlet ports 87, 88 and 89, located respectively at the inner and outerends and the center thereof, each of said ports being opened and closedby a manually-operated gate 90. Disposed di rectly above the sleeve is ahopper 91 which is filled from a chute 92 and is provided with threebranch arms 93, 94: and 95 which communicate respectively with the ports87, 88 and 89, as illustrated in Fig. 12, by reason of which fact, itwill be apparent that the ma-' terial fed into the hopper from saidchute may be discharged therefrom through any one of the ports abovementioned by opening the gate which corresponds to said port and closingthe other two gates, thus regulating to a certain extent, the speed atwhich the material delivered to said conveyor is fed into the interiorof the casing, owing to the taper of the conveyer and of the sleeve inwhich the latter is disposed.

lVithin the body portion of the casing G t is disposed a feed screw 96which is rigidly attached to the turbine shaft 21 and to said bodyportion, below whose lower end it projects, the lowermost blade or wingof the screw which is located proximal to the floor member 58, havingformed integral therewith a notched disk 97.

The operation of the grinding mechanism up to this point, may be brieflydescribed as follows: The material fed to the chute 92, (in the presentinstance, crushed stone), passes therefrom to the hopper 91, whence itis delivered through one or another of the branch arms and, thecorresponding port to the screw 83 by which it is conveyed into theinterior of the casing ti l. From said casing the material is dischargedby the screw 96, whose rotation throws the material against the innerseries of balls 66 by which it is ground, the surfaces of the ballsbeing cleaned by the scrapers 79 which contact therewith. The groundmaterial gradually works its ay outwvardly to the series of balls 67, bywhich it is given a further grimling. After having been subjected to thelast mentioned grinding, the material is gathered up by the scoops 73,during the rotation of the members 59 and (30. it being apparent thatthe latter member, which is rigidly connccted with the casing (tithrough the braces (33, will etl'ect the rotation of the member 5.) byreason of the engagement of its pins 09. with the cars 01. The materialgathered by the scoops will travel upwardly therealong, as said members59 and (i rotate, and will be thrown against the upper series of balls78 by which it will be given a linal grinding, being reduced to thefineness of dust.

The rear half of the grimling mechanism is provided with a series ofshutters 98 arranged in sets of three, as shown in Figs. 10, 12 and 14,each set of shutters being in closed on three sides by a casing 99, therear member of which is formed by the side wall of the cylindricalcasing 57 whose rear half is double, the members thereof being arrangedin spaced relation to each other, to provide a semi-circular outletchamber 100. Each shutter includes a vertical stem 101 which is movableendwise through the bore of a vertical sleeve 102 and terminates at itsupper end in a crank handle 1.03 by means of which it is raised andlowered. The lower end of each stem carries a collar 1041. Each sleeve102 is fitted in a threaded bushing formed upon the top wall of thecasing 57 and is provided with a pair of handles 105 for offecting therotation and resultant endwise movement thereof. The central sleeve ofeach sethas pivotally connected thereto a pair of oppositely-disposed.diverging wings or shutters proper 100, while the end sleeves are eachprovided with a single wing 107 similar to the first mentioned wings,each of the several wings being pivotally connected with thecorresponding collar 101 by a linlt 10S. Owing to the fact, therefore,that the wings 107 extend toward the adjacent wings 100, it will beapparent that the spaces between the lower edges of the wings 106 andthe upper faces of the adjacent wings 107 may be increased or decreasedat will by rotating the stems 101.

The rear wall of each casing 00 is provided with an outlet opening 100which opening forms a means of communication between the interior of thecasing 57 and the chamber 100 the rear wall of the latter being providedwith an opening 110 through which the air escapes, or with a series ofsuch openings if preferred. A strip of fine wire gauze 111 extendsacross each opening. The bottom wall of the chamber 100 has formedtherein a single large outlet opening ll) (or a series of openings)which communicate with the mouth of a. discharge chute (which deliversthe pulverized material to the bin, the chute and bin not being shown)it: being understood that the out-going aircurrent will carry thepulverized material out between the shutters. through the outletopenings S) and 11:3, whence the material passes through the chute tothe bin, the air making its exit through the opening or openings 110. 7

In the modilied form of shutter shown in Figs. and 10. the wings arereplaced by a pair of ilulependently movable sashes 113 and 114, theformer of which comprises an open rectangular frame to which a gauzestrip is secured. while the latter is formed by a single solid strip ofany preferred material. Each sash or shutter is provided with anoperating handle 115.

\Vhile the grinding members in the preferred form of the invention havebeen shown and described as spherical bodies. it is to be understoodthat they may be replaced by cylindrical or frusto-conical roll ers 110as shown in Fig. 13, the alternate rollers of each series havingdiagonally-an ranged intersecting grooves 117 formed therein. Thealternate spherical grinding members of each series are likewiseprovided with intersecting circumscribing grom'cs 11d sald groovesserving to enable the crushing members to more etl'ectively engage andride over the material to be ground and at the same time presenting acutting edge to said material.

By reason of the direct connection between the turbine and the piston.and of the etpii-distant arrangement of the ports and buckets with whichthe piston and the inner shell or cylinder of the turbine. are provided.it will be apparent that the piston is simultaneously lubricated at all.points by the incoming steam and will at the same time have its entireouter wall virtually out of contact with the inner wall of the cylinder.thus resulting in the provision of an'elastic. cushion which surroundsthe piston and reduces to a minimum the friction between the latter andthe cylinder.

In a cement grinding mill the tendency of the grinding members tolateral displacement is very great. and if not prevented, suchdisplacement causes the shaft supporting the grinding members to bearwith great pressure on first one side and another of its bearing withresulting excessive wear so that the life of the shaft and bearing covera very short period. It is not feasible to lubricate the hearings ot theshaft for the reason that the grit from the material passes into thelubricant and defeats the etliciency of same. It will be noted. however.that in the grinding mill herein described the shaft is attached to therotor of a self-centering motor which maintains the shaft in verticalposition, and keeps it free from its bearings.

While the grinding mechanism is designed primarily for pulverizingbroken stone, it is to be understood that any other suitable materialmay be fed to such mechanism for treatment by the same.

hat is claimed is:

1. A grinding mill having a vertical shaft, a casing provided withbearings for said shaft, grinding elements rotated by said shaft andsupported independently thereof to move in a path concentric therewith,and a. self-centering motor having its rotor attached to the said shaftand serving while revolving said shaft to keep the same vertical andfree from its bearings and to cause said grinding elements to operateuniformly in said concentric path.

2. In a grinding mill, the combination with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member comprising inner and outer annular sectionsoperatively connected; braces rigidly connecting the outer section withsaid. shaft; an annular series of grinding rollers interposed betweenthe lower member and said inner section for supporting the latter;spring actuated means for increasing the pressure of the inner member onthe rollers; a separate series of grinding rollers interposed betweensaid lower member and said outer section; and means for feeding thematerial to be ground into the space between said members and intocontact with the first mentioned series of rollers.

3. In a grinding mill, the combination, with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member having a rigid connection with the drive shaft;separate inner and outer annular se ries of grinding rollers interposedbetween said members; means for feeding material into the space betweensaid members to the inner series of rollers, and then to the outerseries of rollers, for successive treatment thereby; an annularhorizontal member disposed above and in spaced relation to said uppermember; an annular series of grinding rollers interposed between saidupper member and said annular member; and means for feeding the materialground by said outer series of rollers to the last mentioned series ofrollers.

f. In a grinding mill, the combination, with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member comprising inner and outer annular sectionsconnected together, one of said sections having a rigid connection withthe drive shaft; an annular series of grinding rollers interposedbetween the lower member and the inner section of the upper member; aseparate annular series of grinding rollers interposed between saidlower member and said outer section; means for feeding material into thespace between said member to the inner series of rollers, and then tothe outer series of rollers for treatment thereby successively; anannular horizontal member disposed above and in spaced relation to theouter section; of said upper member, a series of grinding rollersinterposed between the outer section of said upper member and saidannular member; and means for feeding the n'iaterial ground by saidouter series of rollers into contact with the last mentioned series ofrollers.

In a grinding mill, the combination with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member having a rigid connection with the drive shaft;separate inner and outer annular series of grinding rollers interposedbetween said members; means for feeding material into the space betweensaid members to the inner series of rollers, and then to the outerseries of rollers, for successive treatment thereby. an annularhorizontal member disposed above and in spaced relation to said uppermember; an annular series of grinding rollers interposed between saidupper member and said annular member; and a pair of scoops carried bysaid upper member for feeding the material ground by said outer seriesof rollers to the last mentioned series of rollers.

G. In a grinding mill, the combination, with a. vertical drive shaft, ofupper and. lower horizontal members arranged in spaced relation to eachother, the upper member comprising inner and cute annular sectionsconnected together, one of said sections having a rigid connection withthe drive shaft; an annular series of grinding rollers interposedbetween the lower member and the inner section of the upper member; aseparate annular series of grinding rollers interposed between saidlower member and said outer section; means for feeding mate ial into thespace between said members to the inner series of rollers, and then tothe outer series of rollers for treatment thereby successively; anannular horizontal member disposed above and in spaced relation to saidupper section; a series of grinding rollers interposed between saidupper section and said annular member are a pair of scoops carried bythe outer section of said upper member for feeding the material groundby said outer series of rollers into contact with the last mentionedseries of rollers.

7. In a grinding mill, the combination, with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced I metricallyopposite points, said upper memrelation to each other, the upper memberhaving a pan of vertical openings formed therethrough ad acent its outeredge at draber having a rigid connection with said shaft; separate innerand outer ammlar series of grinding rollers interposed between saidmembers; means for feeding material into the space between said membersto the inner series of rollers, and then to the outer series of rollers,for successive treatment thereby; an annular horizrmtal member disposedabove and in spaced relation to said upper member; an annular series ofgrinding rollers interposed between said upper member and said annularmember; and a pair of scoops having their upper ends titted in theopenings in said upper member and their lower ends contacting with theupper face of said lower member, for feeding the material ground by saidouter series of rollers to the last mentioi'ied series of rollers.

8. In a grinding mill. the combination with a vertical drive shaft. ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member comprising inner and outer annular sectionsconnected together, the outer section having a rigid connection with thedrive shaft, and being provided at diametrically opposite pointsadjacent its outer periphery with a pair of vertical openings; anannular series of grinding rollers interposed between the lower memberand the inner section of the upper member; a separate annular series olgrinding rollers ii'iterposed between said lower member and the outersection ot said upper member; means for feeding material into the spacebetween said members to the inner series of rollers and then to theouter series of rollers -tor successive treatment thereby: an annularhorizontal member disposed above and in spaced relation to said uppersection; a series of grinding rollers interposed between said uppersection and said annular member; and a pair of scoops having their upperends fitted in the openings formed in said upper section and their lowerends resting upon the upper Face of said lower member, for feeding thematerial ground by said outer series of rollers into contact with thelast mentioned series of rollers.

9. In a grinding mill, the combination. with a vertical drivc sha'tit,of upper and lower horizontal members arranged in spaced relation toeach. other. the upper member having a rigid connection with the driveshaft; inner and onto annular series of grinding rollers interposedbetween said members; an annular series of doublc-cndcd scrapersinterposed between said series of grinding rollm's, in contact with thesurtaccs thereof; and means for feeding material into i l the spacebetween saul members and mtol contact initially with the inner series ofrollers.

l0. In a grinding mill, the combination, with a vertical drive shaft, ofupper and lower horizontal members arranged in spaced relation to eachother, the upper member comprising inner and outc. annular sectionsconnect-ed togctlna'. the outer section having a rigid connection withthe drive shatt. and the inner section having a yielding movement withrcl'crencc thereto and to the other section; inner and outer annularseries ot grinding rollers interposed between the sections ol. the uppermember and the lower member; a series of depending scrapers carried byone o'li said sections tor contact with thc rollers of both series; andmeans for feeding the material to be ground into the space between saidmembers and into contact initially with the inner series of rollers.

11. in a grinding mill, the combination. with a vertical drivcshal't'.ol' upper and lower horizontal members arranged in spaced rela tionto each other. the upper member being provided with an axial opening; anannular series of grinding rollers interposed between said member; atleed screw secured to said shall and projecting through the opening .inthe upper member into the space between said meml'icrs; a cylindricalcasing inclosing the upper portion of said screw and having its lowerend fitting in said opening, said casing and screw being rigidlyconnected together; means tor connectin said casing with said uppcrmember, l'or ellccting the rotation ot the latter; a screw conveyor forfeeding material into the upper portion of said casing; a sleevesurroumling said conveyor and provided with a series ot" ports; a gatefor opening and closing each port; and a hopper provided with a separatebranch arm communicating with each port.

12. In a grinding mill. the combination, with a casing, the side wall ofthe casing being provided with an outlet opening; ot a grinding clcmentdisposed within said casing. means lor actuating said grinding element,means tor feeding material into said casing; a plurality of shutters torcontrolling the passage ot the ground material through said outletopening, said shutters being movable imlependcntly ol. each other, eachshutter including a vertical nn'wable stem and a wing pivotallyconnected therewith.

'13. In a grinding mill. the combination with a casing. the side wall ofthe casing being provided with an outlet opening; of a grinding clementdisposed within said casing, means for actuating said grinding ele ment,means tor 'l'ccding material into said casing, a plurality ol shuttersfor controlling the passage ot the ground material through said outletopening, said shutters being movltlt) able independently of each other,each shutter including a vertical sleeve fitted in the upper wall ofsaid casing a stem movable endwise within the bore of said sleeve and awing pivotally connected with the stem and with the sleeve.

14. In a grinding mill the combination of a lower grinding elementcomprising sets of circumscribing concentrically arranged crushingmembers; an upper grinding member; means for feeding the material to thelower grinding element and moving same outwardly for treatment by itsconcentrically arranged crushing members; and means for then conveyingthe material upwardly to the upper grinding element.

15. In a grinding milL the combination of upper and lower grindingelements; a shaft operatively connected with said grinding elements foractuating same; a feed screw secured to said shaft; a cylindrical casingsurrounding said screw and communicating interiorly with the lower grinding element whereby material is fed to the lower grinding elementforinitial grinding; and means for conveying the partially ground materialto the upper grinding ele ment for final grinding.

16. In a grinding mill the combination JOHN N. BOSCH, JR.

Vitnesses WILLIAM E; S'rEiNME'rZ FREDERICK XV. MEISNER.

